Only in Perl

use Acme::Don't;

don't {

  # code here
  # Note that the code in the don't block must be syntactically
  #   valid Perl. 
  # This is an important feature: 
  #   you get the accelerated performance of not actually executing
  #   the code, without sacrificing the security of compile-time
  #   syntax checking.

} while condition();

# And, yes, in strict analogy to the semantics of Perl's magical
#   do...while, the don't...while block is unconditionally not 
#   done once before the test. ;-)